Hypertensive Iridocyclitis and Glaucoma of Horses

Glaucoma in the horse consists of many conflicting “facts” and clinical anecdotes. The horse retina and optic nerve are under severe metabolic stress during the periods of persistent intraocular pressure (IOP) elevation found in glaucoma. Glaucoma in horses eventually results in blindness due to the death of a neuron, the retinal ganglion cell (RGC). Equine recurrent uveitis is also associated with “hypertensive” phases of IOP elevation and RGC death. The pathophysiologic mechanisms of these two eye diseases are distinct and yet also similar. The horse eye can maintain functional vision for prolonged periods despite progressive RGC loss and sustained IOP elevations. The glaucomatous globe of horses also responds to laser therapy of the ciliary body better than other species.